Lens



Sept. 22, 1925.

J. C. WELLS LENS Original, Filed April 18. 1922 .INVENTOR 'J-GWELLS w BYv 6% TORNEY Patented Sept. 22 1925 JOEL C. WELLS, OF SOUTHIBRIDGE,MASSAGHUSETTS.

LENS.

Application fled April 18, 1922, Serial No. 555,250. Renewed August -12,1925.

v To all whom it may concern:

\ Be it known that I, JOEL C. WELLS, a citizen of the United States,residing at Southbridge, in the county of Worcester and State ofMassachusetts, have invented certain new and useful Improvements inLenses, of which the following is a specification.

improvements in lenses and more particu' larly to bifocal lens, the mainobject of the present invention being the provision of a lens of thischaracter which can be produced more nearly achromatic than at thepresent time and also obtain better color correction.

Another object of the invention is the provision of a lens of the abovetype whereln the main body blank of the lens is of a high refractiveindex with a low refractive index button put on the concave side of theblank so that when the two parts are fused and ground down to the propercury'e it will eliminate the usual prismatic effect between. the readingand distance portion of the lens.

With the above and other objects in view the invention consists inthenovel features of construction, the combination and arrangement of partshereinafter more fully,

set forth, pointed out' in the clainis and shown in the accompanyingdrawings, in which- Figure 1 is a longitudinal sectional view taken thrua lens blank minus the reading portion.

Figure 2 is a similar view; showing the button or reading portion inposition ready to be ground down, and

Figure 3 is a similar view showing the lens with the readin portionground down to the concave sur ace of the main lens blank producing asubstantially finished lens.

In the accompanyingdrawings I have illustrated various steps inproducing a lens in accordance with my invention and attention is firstdirected to Figure 1 which illustrates a longitudinal sectional view ofthe main lens blank generally indicated at 1, said blank be ing providedwith the recess 2 at its lower edge for receiving the button whichconstitutes the reading portion of the lens.

The recess 2 which; is formed in the main lens blank is larger at thelower edge of the lens and tends to taper toward the concave surface ofthe lens blank 1 as it extends toward the center of the lens so that thetermination of the recess which is indicated at 3 is disposed below'thecentral portion of the lens blank 1. The lens blank 1 is preferably ofbarium crown or flint glass while the button 4 which constitutes thereading portion of the lens is preferably of a relatively light glassand is fitted .into the recess 2 as shown in Figure 2, said button beingsecured within the recess in any manner wellknown in the This inventionrelates to new and useful art of lens manufacture. 1

After the button 4 has been fitted into the recess 2 the lens is grounddown from the state illustrated in Figure 2 to a substantially finishedlens as shown in Figure 3 wherein it will be noted that the upper curvededge of the button or. reading portion tapers directly into the concavesurface of the main lens blank 1, thereby forming a finished lens inthismanner and wherein the blank 1 is of a high refractive index and thereading portion of a low refractive index attached to the concavesurface of the high index blank. A lens is produced whichwill be morenearly achromatic and provide for better color correction than the lensproduced in a similar manner at the present time.

In the present methodof producing bifocal lenses it is the practice toform the re cess 2 with the tapering portion 3 terminating to the edgeof the lens with the thicker portion of the button disposed at a pointremoved from the center of the lens, but the objectionable feature in alens of this character is the fact that a certain amount of achromaticcondition is present at the junction between the reading and distanceportion, and it is therefore one of the main objects of my invention toprovide a lens wherein the extreme tapering portion of thebuttonterminates directly into the concave curve of the lens so as toreduce to a minimum the prismatic effect generally noted when the visionofthe eye passes from the reading portion to the distance portion andvice versa. I I

It will be obvious to' those skilled in the art, thatbeca'useof thereading portion being of a lower refractive index than the distanceportion, the curvature of the recess 2 will have to be of a greaterradius than that of the main blank surface, and it is most preferablethat the recess be tangent to the curvature of the main blank as clearlyshown in the drawings.

What Iclaiinis: I

1. A multifocal lens, comprising a major blank of glass of high index ofrefraction, having a concave inner surface, and a convex outer surface,said inner surface having a wedge shaped recess disposed below thecenter of the blank, the apex of the wedge pointing upwards and thewidest portion of (the wedge being locatedat the bottom, a wedge ofglass of low index of refraction secured in the recess, the outersurface of the wedge insert being finished to the same curvature as theinner surface of themajor blank, and the inner surface of the wedgeinsert being, finished to the same curvature pointm upwards and thewidest portlon of as the inner surface of the recess, as and for thepurpose. described. 7 a p 2. A multifocal lens, comprising a major blankof barium glass, having a concave inner surface and a convex outersurface, said inner surface havin a wedge shaped recess disposed below te center of the blank, the apex of thewedge pointing upwards, the widestportion 'of the wedge being located at the bottom, and a wedge of glassof low index of refraction secured in the recess, the outer surface ofthe wedge insert being finished to the same curvature as the innersurface of the major blank,

and the inner surface of the wedge insert being finished to the samecurvature as the inner surface of the recess, as and for the center ofthe blank, the apexeof the wedge the we ge beinglocated at the bottom, aWedge of lass of low index of refraction secured in t e recess, theouter surface of the wedge insert being finished to the same curvatureas the non-recessed portion of the major-"blank on therecessed side andthe inner surface of the Wedge insert being finished to the samecurvature as the face surface of the recess.

.' JOEL o. WELLS.

